Froggy style

I am new to this forum and I need to get connected. I have been rescuing frogs for years from window wells in my neighborhood. I purchased four splash back galacs 17 months ago. They started to make calls last fall but then stopped. They have recently begun to make calls again. They are pairing up. Two are sleeping in the bromeliad and two at the top of my vivarium. The two at the top of the vivarium are also going in and out of the coconut hut. I am so excited and nervous. How long do they usually make the calls before the egg laying begins? Why are mine making calls for a short time period? Maybe I have just one shy male with three females. If I have two breeding pairs... is it be bad to have two pairs in one tank? I have three more empty tanks. I have one HUGE beautiful new tank with waterfall that is completely set up...waiting for babies.
Thanks for your advise, in advance.
Sincerely,
Jayne